How to read a Bosch error code
On Bosch displays (Kiox, Nyon, SmartphoneHub, Purion 200), an error code appears in the form Exxx. On Smart System, it shows in the Bosch eBike Flow app or on the Kiox 300/500. All codes are stored in the motor — accessible via Bosch DiagnosticTool (authorised dealer only).
Here are the 12 codes you'll encounter most often.
E007 — Battery communication error
Symptom: motor cuts out abruptly, battery still displays but is unusable.
Likely causes:
- Battery/motor connection terminal corroded or loose
- Battery BMS rejecting communication (faulty cell)
- Communication cable damaged (rodent damage, impact)
First action: switch everything off, disconnect the battery, wait 30s, clean the contacts with alcohol, reconnect firmly. If it persists → dealer DiagnosticTool.
E010 — Display communication error
Symptom: display stays on "..." or won't turn on, but motor runs in degraded mode.
Causes:
- Display-to-motor cable disconnected (check 8-pin connector)
- Display faulty (rare)
- Interrupted firmware update
Action: reconnect the display cable, restart. If display remains unresponsive → replace display cable (~£40).
E015 — Torque sensor error
Symptom: erratic assistance, sometimes too strong, sometimes absent.
Causes:
- Torque sensor drift (appears after >15,000 km)
- Calibration required after crankset change
Action: run the calibration procedure via Flow app (Smart System) or DiagnosticTool. If no improvement → sensor replacement (workshop intervention, £240-320).
E020 — Motor overheating
Symptom: gradually reduced assistance, sometimes total cut-off, display shows a thermometer.
Causes:
- Prolonged effort in boost mode at high percentage
- Motor housing ventilation blocked (mud, grass)
- Very high ambient temperature
Action: stop, let cool for 15-20 minutes, clean the housing, resume in Eco mode. On the CX model, the safety threshold is 85°C.
E025 — Speed sensor
Symptom: assistance maintained beyond 25 km/h or cut off too early.
Causes:
- Speed sensor magnet displaced (on rear wheel)
- Hall sensor faulty
- Magnet-to-sensor distance incorrect (>5 mm)
Action: visually check the magnet (at rear spoke level) and its distance to the sensor. Readjust if needed. Run a test again at 5-10 km/h.
E030 — Battery voltage out of range
Symptom: startup refused, or cut-off as soon as you demand torque.
Causes:
- Battery very low (<10%)
- Faulty battery cell (imbalance)
- BMS cutting out for safety
Action: charge the battery completely. If E030 remains after 100% → BMS diagnostics at dealer (may require battery replacement under warranty if <2 years).
